Electronic amplifiers are used for increasing a power and/or an amplitude of various electronic signals. Most electronic amplifiers operate by using power from a power supply, and controlling an output signal to match the shape of an input signal, while providing a higher amplitude signal.
One widely used type of electronic amplifier is a power amplifier, which is a versatile device used in various applications to meet design specifications for signal conditioning, special transfer functions, analog instrumentation, and analog computation, among others. Power amplifiers are often used in wireless applications, and may employ radio-frequency (RF) amplifier designs for use in the RF range of the electromagnetic spectrum. An RF power amplifier is a type of electronic amplifier used to convert a low-power RF signal into a signal of significant power, such as for driving an antenna of a transmitter, for example. RF power amplifiers are also used to increase the range of a wireless communication system by increasing the output power of a transmitter.
Power amplifier properties of linear operation and efficiency may be inversely proportional to one another. It is desirable to power amplifier efficiency, while reducing non-linear operation. One approach for improving efficiency of the power amplifiers is through envelope tracking (ET). Power supply envelope tracking circuitry, however, increases the cost of a mobile device. Thus, some lower cost mobile devices do not have this feature.